Drilling rigs

ABSTRACT

A drilling rig has a fluid pressure crowding device operated through a pressure accumulator so that no external energy input is required to maintain the crowding action during drilling. By use of differential piston crowding rams, the accumulator can be arranged in a closed circuit and the rams moved against its crowding action when it is required to reposition the drill shaft drive member through which the crowding action is transmitted.

United States Patent Virgo 1 July 4,1972

[54] DRILLING RIGS [72] Inventor: James Rusell Virgo, Belstead, England [73] Assignee:. The British Steel Piling Company Limited,

Claydon, Ipswich, Suffolk, England [22] Filed: Nov. 2, 1970 [21] Appl. No.: 86,251

[30] Foreign Application Priority Data Nov. 3, 1969 Great Britain ..53,800/69 [52] US. Cl. ..173/149, 173/157, 173/159 [51] Int. Cl. ..E26c 5/10 [58] FieldoiSearch ..l73/149,148,141,151,154,

[56] References Cited UNITED STATES PATENTS 2,169,678 8/1939 Caldwell ..173/149 2,188,107 1/1940 Caldwell et al. ..l73/l49 2,393,603 1/1946 Beeth ..l73/149 3,094,312 6/1963 Woolgar ..l73/l49 X 3,240,278 3/1966 Witwer ....l73/15l X 3,525,404 8/1970 Newman et al. ..l73/l58 X Primary ExaminerDavid H. Brown Attorney-Larson, Taylor and Hinds [5 7] ABSTRACT 7 Claims, 3 Drawing Figures P'A'TENTEDJULM 1972 3. 674. 098

SHEET 1 or a DRILLING RIGS tant when drilling in hard formations, when the power 1 required for rotating the drill bit is greatest.

It is an object of the present invention to provide means whereby power for crowding pressure is not required to be supplied during drilling so that with a given power unit, it is possible to obtain an improved drilling rate, the whole power input then going to rotate the drill shaft.

According to the invention, there is provided a drilling rig comprising a carrier on which a drill shaft is mounted through a rotary drive member, means being provided to crowd the shaft while it is being rotated with said drive member, the drive member being arranged to be lifted to a starting position for said crowding action by fluid pressure means and a pres sure accumulator being so arranged with said fluid pressure means that the crowding force can be applied through the fluid pressure means and the drive member to the shaft during rotation of the shaft for a drilling operation from the pressure in said accumulator without the input of an external pressure supply.

With such an arrangement, the fluid circuit containing the accumulator may act as a closed circuit requiring fresh pressure fluid only for replacement of leakage losses.

The crowding action now being obtained from the accumulator and being determined by its size, it is possible to obtain a relatively high force with a relatively small hydraulic pump in comparison with conventional arrangements. A faster crowding action can be obtained in softer soils than would otherwise be the case, and when drilling hard rock layers a substantial crowding force can be applied while a maximum power input is applied to the rotary drive which is an advantage in such drilling conditions.

Conveniently, a common accumulator is provided for a plurality of crowding rams that act upon said drive member and the accumular is secured adjacent the drive member and on the carrier which supports the drive member.

Preferably, the crowding action is performed by one or more double-acting rams, the re-positioning of the drive member by a return movement after a crowding movement being arranged to be carried out by admitting pressure fluid to the underside of the or each ram so as to urge fluid from the upper side of the or each raminto the accumulator as the drive member rises on the return movement.

An embodiment of the invention will be more particularly described with reference to the accompanying drawings wherein:

FIG. 1 is a side elevation of crawler-mounted drilling rig according to the invention;

H6. 2 is a side elevation to a larger scale of the carrier and its associated parts in the rig ofFlG. l, and

FIG. 3 illustrates the hydraulic ram circuit of the rig of FIG. 1.

In FIG. 1 of the drawings, a crawler vehicle 2 has a jib arm 4 from which drill shaft or kelly 6, which may be in several parts, is suspended through a swivel mounting 7 permitting free rotation of the kelly. A support frame 8 is mounted to the vehicle at a lower pivot joint 10 and is secured in its upper region through hydraulic rams 12 so that the frame can be tilted backwards and forwards to align the kelly. Clamped to a pair of side columns 14 of the frame is a carrier 16 on which are mounted the driving mechanism and a pressure-applying or crowding assembly for the kelly 6 shown in more detail in FIG. 2.

The crowding assembly comprises a sleeve 18 rotatably mounted in a collar 20 to which are fixed arms 22 that project in diametrically opposite directions to be rams to the upper ends of a pair of hydraulic rams 24. The rotatable engagement between the sleeve 18 and collar 20 includes anti-friction thrust bearings (not shown) that prevent relative axial movements between the parts so that the sleeve will move up and down with the collar as the collar is displaced by the crowding rams 24. An upper plate 28 is supported by springs 30 above the upper end of the sleeve 18 to buffer the shock load that would be imposed if the kelly is dropped to rest upon its top flange 32, which will then strike the plate 28.

To drive the kelly, the sleeve 18 is rotatable by means of an hydraulic drive comprising an hydraulic motor 34, torque converter 36 and an encased bevel gear 38 to a spur gear ring (not shown) on the ring 18. The kelly, and its receiving hole through the sleeve, are both of square section and the application of a rotary drive input to the sleeve has'the effect of locking the kelly frictionally to the sleeve so that it is then also axially fixed relative to it. During rotation of the kelly therefore, the application of pressure fluid to the rams 24 causing them to contract applies an axial feed movement through the sleeve to the kelly.

When the crowding rams are fully contracted, the rotary drive is stopped and the rams extended to lift the collar and sleeve, which will then rise independently of the kelly since this will no longer be frictionally engaged by the sleeve. The re-start of the rotary drive with the sleeve raised grips the kelly again and crowding pressure can then be applied once more by the rams 24.

Hydraulic fluid is supplied to the positioning rams l2 and the crowding rams 24 from a common pump 42 through respective control valves 44, 46 for the crowding rams 24 and 48 for the positioning rams 12. With the valves in the central or neutral position, fluid is returned direct to a reservoir through line 52 so that there is little or no back pressure against which the pump has to work. Line 50 from the valve 44 to the upper sides of the crowding rams 24 has an accumulator 54 in it so that fluid is forced from the accumulator and pressure continues to be applied to contract the rams alter the valve 44 has been moved from a pressure-fluid supplying position to the neutral position. As can be seen in FIGS. 1 and 2, the accumulator 54 is secured on the carrier 16 adjacent the rams 24. A pressure relief valve 56 is connected to both sides of the rams 24 and to the accumulator 54.

In operation, therefore, when drilling is to start, the kelly is lowered to the ground or into the already started hole until its suspending cable on the jib 4 has become slack. The rotary drive is then applied to the sleeve 18 and immediately following this the valve 46, which has previously applied pressure oil to the undersides of the crowding rams to extend these rams against the pressure from the accumulator and so raise the collar and sleeve, is switched to allow the undersides of the rams 24 to drain to the reservoir. The accumulator pressure thus applies a crowding action to the kelly that has become frictionally engaged with the sleeve so that it is urged into the hole as it rotates. When the full stroke of the rams 24 has been utilized, the rotation of the sleeve is stopped and the crowding rams raised by re-applying pressure fluid to the undersides of the rams. The cycle can then be repeated.

It is to be noted that in this cycle of operation, the crowding action requires no external power input while the drilling is proceeding and the full engine power of the rig is therefore available for rotating the kelly. Also, since the pressure fluid is continuously retained in the upper ends of the rarns 24 and the accumulator there is no need for re-charging this part of the it may be noted that the accumulator is fed from the same pressurizing pump 42 as is used to raise the rams 24 for the return movement of the collar and sleeve. The fact that the piston rods extend through the upper ends of the ram cylinders, however, means that at a given fluid pressure a greater force can be generated on the underside of each piston than on the other side so that the pressure supply from the pump 42 can raise the rams, when required, against the continuing force applied from the accumulator.

What is claimed is:

1. A drilling rig comprising, in combination, a carrier, a rotary drive member supported on the carrier, a drill shaft adapted to be rotatably engaged by the drive member, fluid pressure means connected between the carrier and the drive member, a pressure accumulator adapted to be connected in circuit with the fluid pressure means, said fluid pressure means being operated by pressure from the accumulator to apply a crowding force through the drive member to the shaft while the shaft is being rotated by the drive member, said crowding force being generated thereby without the input of an external pressure supply during the rotation of the shaft.

2. A drilling rig according to claim 1 having a plurality of crowding rams in said fluid pressure means acting upon the drive member, said pressure accumulator being common to both rams feeding pressure fluid to said rams for the crowding effect thereof.

3. A drilling rig according to claim I wherein the accumulator is secured adjacent the fluid pressure means and on carrier that supports the drive member.

4. A drilling rig according to claim 1 wherein at least one double-acting ram is comprised in the fluid pressure means, the crowding action being performed by displacement of said at least one ram to move the drive member downwards, fluid pressure control means in circuit with said at least one ram being operable on completion of a crowding movement to admit fluid into said at least one ram so as as to move the drive member upwards while urging fluid from said at least one ram to the accumulator.

5. A drilling rig according to claim 4 wherein a commo pressure source supplies the accumulator and said underside of said at least one ram and a differential area piston is contained in said at least one ram whereby for a given fluid presthe sure the crowding movement pressure force acting in the ram is less than the return movement force.

6. A drilling rig according to claim 1 the drive member comprises a sleeve through which the shaft passes and a non- 'rotatable collar connected to said fluid pressure means engages the sleeve to transmit the crowding force thereto.

7. A drilling rig according to claim 1 wherein a fluid circuit containing the accumulator is arranged to act as a closed circuit requiring fresh pressure fluid only for replacement of leakage losses. 

1. A drilling rig comprising, in combination, a carrier, a rotary drive member supported on the carrier, a drill shaft adapted to be rotatably engaged by the drive member, fluid pressure means connected between the carrier and the drive member, a pressure accumulator adapted to be connected in circuit with the fluid pressure means, said fluid pressure means being operated by pressure from the accumulator to apply a crowding force through the drive member to the shaft while the shaft is being rotated by the drive member, said crowding force being generated thereby without the input of an external pressure supply during the rotation of the shaft.
 2. A drilling rig according to claim 1 having a plurality of crowding rams in said fluid pressure means acting upon the drive member, said pressure accumulator being common to both rams feeding pressure fluid to said rams for the crowding effect thereof.
 3. A drilling rig according to claim 1 wherein the accumulator is secured adjacent the fluid pressure means and on the carrier that supports the drive member.
 4. A drilling rig according to claim 1 wherein at least one double-acting ram is comprised in the fluid pressure means, the crowding action being performed by displacement of said at least one ram to move the drive member downwards, fluid pressure control means in circuit with said at least one ram being operable on completion of a crowding movement to admit fluid into said at least one ram so as as to move the drive member upwards while urging fluid from said at least one ram to the accumulator.
 5. A drilling rig according to claim 4 wherein a common pressure source supplies the accumulator and said underside of said at least one ram and a differential area piston is contained in said at least one ram whereby for a given fluid pressure the crowding movement pressure force acting in the ram is less than the return movement force.
 6. A drilling rig according to claim 1 the drive member comprises a sleeve through which the shaft passes and a non-rotatable collar connected to said fluid pressure means engageS the sleeve to transmit the crowding force thereto.
 7. A drilling rig according to claim 1 wherein a fluid circuit containing the accumulator is arranged to act as a closed circuit requiring fresh pressure fluid only for replacement of leakage losses. 